Physical and thermal insulation properties of the composites based on seawater-neutralised bauxite residue

The objective of this study is to evaluate the possibility of using bauxite residue (BR), which is a highly hazardous waste, as a filler in thermoset polymer matrices for applications in insulating construction materials to minimise heat loss in buildings. Unsaturated polyester resin (UPR) blended with the seawater-neutralised BR in a ratio of 0–60 vol.% was transformed into a solid via a crosslinking process at room temperature. The pristine polyester and BR–UPR composites were characterised to ascertain their structural, physical and thermal properties. The results indicate that BR is a good filler that can be used with UPR to develop thermal insulation/construction materials. The UPR composite containing 40 vol.% BR is considered to be the optimum mixture with respect to the tested physical and thermal properties because it utilises a large amount of filler and shows promising thermal insulation characteristics with a thermal conductivity of 0.096 W/(m∙K), a thermal diffusivity of 0.161 mm²/s, a 24–h water retention of 0.15 % and a bulk density of 1484 kg/m³. Furthermore, the thermal stability of the prepared composites is positively influenced by the incorporation of BR. The overall weight loss upon heating to 900 °C decreased from 99.85 % (pristine polyester) to 46.68 % (60 vol.% BR composite).